A process that is critically important to the function of blood neutrophils and monocytes is the enzymatically controlled activation of molecular oxygen. A variety of potent oxidizing agents produced by these blood cells are released into the phagolysosome, where they serve as potent micobicidal agents, or into the extracellular space, where they mediate pathological tissue destruction in addition to several physiologic functions. The long term goal of this project is the identification of the control mechanisms that are responsible for the activation and subsequent deactivation of oxidant generation by specifically stimulated blood neutrophils and monocytes. The knowledge gained from these studies will be pertinent to the understanding of such diverse pathologic processes as the adult respiratory distress syndrome, anoxic or ischemic tissue injury and infarction, certain forms of vasculitis, acute and chronic inflammatory arthritis, and carcinogenesis resulting from chronic inflammation. Recent studies directed at the secondary prevention of pathologic tissue damage that occurs subsequent to stimulated neutrophil or monocyte oxidant generation have centered on the use of a variety of enzymatic or non-enzymatic anti-oxidants or scavengers. While these agents have been shown to be effective in certain animal models of acute or chronic inflammation, their major disadvantage in clinical applicability has been difficulty in effectively delivering these agents to local sites of active inflammation. More detailed knowledge of the control mechanisms of oxidant radical generation may reveal ways to modulate this process by pharmacologic agents that would exert their effects directly on the phagocytic cells that generate these oxidants. The specific aims of this project are to purify the cytosolic cofactor from normal unstimulated human neutrophils that serves as the activation cofactor of the NADPH oxidase in the cell-free activation system. The cholera- and pertussis toxin- insensitive G protein that regulates cell-free activation of the NADPH oxidase will be purified in a form that is activatable in the cytosolic cofactor-dependent cell-free system.